Green’s Dictionary of Slang

prattling-box n.

a pulpit.

1723		‘Whipping-Tom’ Democritus III 7: The vociferous Holderforth, was as bold and sawcy in his pratling Box, as if the Deity and all Mankind had ow’d him Money.
1734		C. Johnson Hist. of Highwaymen &c. 87: The Fanatick Parson was ashamed of himself, and descended from his Pratling Box, without proceeding any further in his Harangue.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1862		E. de la Bédollière Londres et les Anglais 317/1: prattling box, chaire à prêcher.